Portion of an electronic mouse



FIG. 1 is a front perspective view of a portion of an electronic mouse showing my new design;

FIG. 2 is a rear perspective view thereof; and,

FIG. 3 is a top view thereof.

The broken line showing of various regions and the unshaded areas there within form no part of the claimed design. 

The ornamental design for a portion of an electronic mouse, as shown and described. 